Safety relay system

Abstract

A safety relay system includes one or more additional input units each for sending safety input from a safety component, a master unit for receiving the safety input from the additional input unit and providing safety output to operate a safety relay based on the safety input, a safety information line for transferring safety information between the units, a non-safety information line for transferring non-safety information separate from the safety input, the non-safety information being information concerning an operation state of each safety component or each unit, and a non-safety information output section for outputting the non-safety information transferred on the non-safety information line.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] Th present invention relates to a high-reliability safety relay system suited for use, for example, to drive a target load only if a plurality of input conditions concerning safety check, etc., all hold. [0003] 2. Description of the Related Art [0004] A safety measure apparatus is used from the necessity for a safety measure in various quarters. For example, a machine tool, a pressing machine, a robot, a packing machine, an elevator, and the like are used at a manufacturing location, and various safety measures become necessary to protect workers from the machines, the apparatus, etc. For example, when an anomaly occurs, power supply to the machine is cut off, thereby stopping the mechanical operation for securing safety for workers. To construct such a system, a safety relay apparatus is used. [0005] The safety relay apparatus opens and closes electrical contacts to control energization. Some safety relay apparatus...

AI Technical Summary

Benefits of technology

[0011] It is an object of the invention to provide a safety relay system for making it possible to add non-safety information relevant to safety information without affecting the safety information for easily maintaining, recovering, redesigning, etc., the safety system.

[0013] The safety information transmitted on the safety information line is not affected by the non-safety information transmitted on the non-safety information line and safety output of the master unit operates based on the safety information transmitted on the safety information line and does not depend on the non-safety information on the non-safety information line. Accordingly, the state of each safety component, error information, and the like can be transmitted to the master unit according to the non-safety information, and it is made possible to rapidly recover the system from trouble based on the information. As the non-safety information is separated from the safety information and is sent on the separate line, the circuit of the non-safety information can be simplified. The non-safety information has no effect on the safety information, so that the advanced safety standard can be met without affecting the reliability of the circuit concerning the safety information.

Problems solved by technology

To make the apparatus or system compliant with the various standards including EN954-1, etc., described above, it is necessary to duplex the circuitry for handling safety information and provide a self-check function and generally the circuit design becomes complicated.

On the other hand, even if the system is configured so as to be able to check the safety state by duplexing the circuitry, etc., if the cause, location, etc., of an accident when the system becomes down cannot be detected or determined without any measure.

However, if such detailed information concerning safety information is used as safety input, the circuit for handling the information also requires facilities of duplexing, self-check, etc., for safety, and the circuitry becomes furthermore complicated; this is a problem.

If design change occurs in the system, construction of the safety system responsive to the design change needs to be again designed, and the job is extremely intricate.

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